Apparatus for surveying a tank bottom



Feb. 7, 1961 J. LERNER 2,971,154

APPARATUS FOR SURVEYING A TANK BOTTOM Filed Oct. 21, 1958 2 Sheets-Sheet 1 x f f H6 FIG. I.

TO EXCITER CIRCUIT c TO DETECTOR and I6 MEASURING CIRCUIT rn-nas, 40 II II Is JQF QX I 560 1 1 1 I62 64 M62 -l62 Y 154 154 154 I co c. 1 00 l 1 i L T INVENTOR.

JULIUS LERNER F16 3.

ATTORNEYS Feb. 7, 196 1 J. LERNER APPARA'IUS FOR SURVEYING A TANK BOTTOM 2 Sheets-Sheet 2 Filed Oct. 21, 1958 INVENTOR.

JULIUS LERNER FIG. 2.

ATTORNEYS United States Patent- 2,971,154 APPARATUS FOR SURVEYING A TANK BOTTOM Julius Lerner, Drexel Hill, Pa., assignor to Sun Oil Company, Philadelphia, Pa., a corporation of New Jersey Filed Oct. 21, 1958, Ser. No. 768,715

3 Claims. (Cl. 324-61) This invention relates generally to apparatus for surveying the bottom of a tank, and more particularly to improvements in apparatus for determining elevations at selected locations on the bottom of a tank for the purpose of making a contour map and thereby ascertaining the shape of the tank bottom.

It is common practice in oil refineries andchemical plants to store materials such as asphalt and the like in large diameter upright cylindrical tanks provided with flat bottoms that are supported upon concrete foundations. The areas of a tank bottom spanning the underlying foundations sag somewhat under load, making periodic inspections and surveys of the tank bottom neces- 'sary. The shape of the tank bottom is determined, and fromthis it is possible to determine the stresses to which the tank bottom is being subjected. The apparatus uti: lized in making the survey preferably operates within the tank while the tank is loaded to capacity. It should be selectively positionable for successively scanning different areas of the tank bottom, and it should be provided with means for giving a visual indication of and'identifying the point on the tank bottom being scanned. Accordingly, it is a general object of the present invention to provide improved apparatus for the purpose aforesaid.

An object of the present invention is to provide such apparatus including means operable for generating electric signals indicative of the tank bottom shape.

Another object of the present invention is to provide such signal generating means comprising condenser plate means mounted upon the apparatus for movement thereby over the tank bottom in close proximity thereto for scanning the same.

Yet another object of the present invention is to provide such signal generating means comprising condenser plate means connected in electric circuit with the tank bottom and mounted upon the apparatus for movement thereby over the tank bottom in close proximity thereto for scanning the same.

Other objects and advantages of the present invention Figure 2 is a vertical section showing a modification of i the apparatus constructed in accordance with and embodying the principles of the present invention;

Figure 3 is a wiring-diagram ofthe electric system showing, in particular, elements which may be'involved in securing the desired electric signals." V

Referring particularlyto Figured, the exemplary ap';

paratus constructed in accordance with and embodying the principles of the present invention comprises a storage he psaho tom. 1.10 e t n ing horizontally. Marlin-s 2;

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drical wall 112 extending uprightly from the tank bottom and a top 114 extending horizontally. The tank bot, tom 110 is supported upon a concrete foundation 116 under the central area thereof and a concrete foundation 118 under the marginal area thereof.

Centrally disposed within the storage tank is a tubular shaft 120, the lower terminal portion of which is revolubly journalled in a fitting 122 anchored to the tank bottom 110. An upper end portion of the tubular shaft projects through the top 114 of the tank and is revolubly; journalled in a fitting 124 secured to the top 114 of the tank.

Above the foot of the tubular shaft 120 is -a member, generally designated 126, an intermediate portion of which is in the form of a sleeve 128. This member 126 is fitted over the shaft 120 through the medium of the slteve 128, being rigidly secured thereto in any suitable manner. The opposite end portions of the member 126 are in the form of sleeves 130, which respectively receive the inner end portions of a pair of frame members 132 that extend horizontally outwardly from the shaft 120 in parallel laterally spaced relation to one another. The outer endportions of the frame members 132 are received respectively by a member generally designated 134, being rigidly" secured thereto by any suitable means. Thus the frame members 132 and the members 126 and 134 interconnecting these frame members provide a rigid'carriage member or frame structure. For supporting the outer end portion of this frame structure the member 134 is suitably; fitted with a wheel 136 operating upon the tank bottom 1 10 and disposed close to theupright'tank wall '112, over the foundation 118. f '1' The upper terminal portion of the tubular shaft 120? has fixed thereto a bevel gear 138 meshin'g'with a com' panion bevel gear 140. The latter is fixed tothe output shaft of a motor and change speed unit 142 supported: upon a platform 144. f

Carried by the tubular shaft 120 and extending upwardly in longitudinal continuation thereof is a rod 146 to which there is attached a pointer 148. Underlying the latter is an'annular dial 150, stationarily mounted in any' suitable manner. The position 'of the pointer 148 over the dial 150 indicates the position of the rigid framestructure within the tank. Depending from longitudinally spaced portions of the rigid frame structure are a plurality of easing members 152 within each of which are housed certain elements of the electric system, as will appear hereinafter. Also depending from the rigid frame structure are a plurality of insulated conductors each of which may take the form of a metallic plate 154 provided with a thin coat of an inert insulating material 156 such as Teflon. An inner group of these insulated conductors is closely; associated respectively with the casing members 152; while an outer group is associated with the outermost portion of the rigid frame structure. All of the insulated conductors of both groups thereof are shown in Figure 3,- but in Figure 1, to avoid confusion, while all of the insulated conductors of the inner group thereof are shown,. only one of the insulated conductors of the outer group, thereof is shown. All of these insulated conductors are suspended from the frame members 132 by means of hangers indicated at 158, thereby being disposed in the same horizontal plane, in close proximity to thetank bottom 110. It will be understood that the outer group or insulated conductors are all disposed directly over' the concrete foundation 118. i

Each plate 154 o'fth'e inner group" thereof is provided with a conductor-160 -extending into 'the associate'd casing. 152:" Each lplate 15'41'6f the outergrou pftl'i'ereof is provided with a conductor -1 62 extending into 'one of thefcasings --152; conductor- 164 is connected to: the top 114 ,0f.,the'. ..t&nk, prox m e t e shaft .120.

extendsdownwardly and then outwardly across the tank bottom 110 branching into; each of the casings 152. Extending downwardly freely intothe tubular shaft 120 are coaxial cables 20, 20"and 20". These cables pass freely through the wall of the shaft 120 and 166 and continue outwardly each into one of the casingrnembers 152, as shown. i '7 The electric system per, se may take theform of an electric system disclosed in the copending application of Elbert Neil Shawhan, Serial No. 449,437, filed Aug: ust 12, 1954, which copendingj application describes, in connection with Figures, 1, 2 and 3 of the. drawing, an electric system comprising exciting, signal generating, and detecting and measuring circuits. Referring. particularly to Figure 3 of the. instant applicatiomshowing the signal generating circuit, it will be noted that the same. numerals have been utilized, where applicable, as in the aforesaid copending application. It should be observed that all of the signal generating. apparatus, except the condenser plates 154, is housed within the, cas. ing members 152, and that the tank is grounded. Reference may be. had to the copcnding application aforesaid for the disclosure ofdetails ofconstruction and operation of the electric system not given herein.

Each plate 154 of the inner. group thereof isdispos'ed overa tank bottom area that is subject to sagging under load. The plate serves as one of the plates of a test capacitor C while the underlying area of the tank bottom, 110 serves as theother plate of the test capacitor C Each plate 154 of the outer group thereof is disposed over an area of the tank bottom 110 that cannot sag, i.e., as noted hereinbefore, an area adjacent the cylindrical tank wall 112, over'the foundation 118. The plate serves as one of the plates of a reference capacitor C while the underlying area of the tank bottom 110 serves as the other plate. of the reference capacitor C It will be appreciated thatthe capacitance at a given plate 154 will depend upon the vertical spacing between that plate 154 and the tank bottom area immediately therebeneath, in con equence of which the several capacitances C may be different fro-m one another and from the reference capacitance C which latter is the same-at each plate 154 of the outer group thereof. By operation of the electric system as described in the copending application aforesaid, the differences between the several capacitances C and the reference capacitance C may be measured with a high degree of accuracy thereby to obtain an indication of the shape of the tank bottom 112 at the location being scanned.

Having completed the investigation with the rigid frame structure extending outwardly from the shaft 120 in a given direction, the operator may swing the frame structure about the axis of the shaft 120 successively to other different positions, the operation being repeated in each position. For this purpose, preferably, the electric motor 142 is of the reversible type so that it may be operated to swing the rigid frame structure through 360" about the axis of the shaft 120 and back again to its initial position. Suitable means (not shown) may be provided to limit swinging movement of the frame structure in either direction. The power output of the electric motor 142 is transmitted through the set of bevel gears 140 and 138 to the tubular shaft 120. As stated hereinbefore, the shaft 120, member 126 and the frame members 132 are rigidly secured together, in consequence of which the frame structure is swung about the axis of the shaft 120 when the motor 142 is operated, the

outer end of the frame structure being carried by the wheel 136 operating on the bottom or the tank.

Having scanned the bottom of the tank with the frame structure in a number of different positions, and having obtainedfthe desired indication of the tank bottom shape at each of said positions, the operator may draw a contour: map of the tank bottom anddetermine the dea s ms.

4. gree to which it has sagged under load and the stresses to which it is being subjected under load.

Now referring to Figure 2, the exemplary modified apparatus constructed in accordance with and embodying the principles of the present invention is similar in construction and operation to that already described, except as indicated hereinafter. Where applicable, the same numerals. have been applied to corresponding parts ofthe two exemplary embodiments.

In the modified. form of. the invention, a single casing member 152 is mounted, by means not shown, upon the rigid framestructurefor shifting movementlongitudinally thereof in either direction. For shifting the casing memher, a cable section 200 is secured by'one end thereof to the casing member and trained under a pulley 202 depending from the frame structure, proximate the centrally disposed tubular shaft, designated 204, from whence it extends upwardly freely through guide brackets 206 projecting laterally from the shaft 204 and thenthrough the top 114 of the tank. In addition, a second cable sec tion 208 is secured by one end thereof to the casing member and trained about a pulley 210 mounted upon the outermost portion of the frame structure, from whence it extends'inwardly and is trained under a pulley 212 mounted upon the frame structure, proximate the tubular shaft 204, being then extended upwardly with the cable section 200 freely through the guide brackets 206 and the tank'top 114. It will be apparent that the casing member 152 may be positioned as desired along the length of the frame structure by manipulation of the cable sections 200 and 208.

One plate 154 is mounted, as by a. member indicated at 214, for movement with the casing member 152, and the conductor extends from this plate into the casing member 152. The conductor 162 extends from the other plate 154 freely through a tubular standard 216 that is mounted upon the frame structure for movement therewith, extends to a second standard 218 that is mounted upon the casing member 152 for movement therewith, and then freely therethrough and into the casing member 152. The conductor 164 extends from the top 114 of the tank'to the standard 218, and then freely therethrough and into the casing member 152. The coaxial cable 20 extends downwardly freely into the tubular shaft 204 and passes freely through the Wall of the shaft 204 at 220, from whence it extends to the standard 216, freely therethrough and into the casing member 152.

The electric system for this modified form of the invention may be essentially the same as that indicated hereinbefore as being suitable for the form of the invention illustrated in Figure 1. However, only one sensing or signal generating circuit is utilized. The cable sections 200 and 208 may be manipulated to selectively shift the casing member 152 and the plate 154 and standard 218 mounted upon the member 152 as a unit longitudinally of the frame structure, sufficient slack being provided in the conductors 162, 164 and the coaxial cable 20 to accommodate this movement. The plate 154 mounted upon the casing member 152 and the underlying tank bottom area serve as the plates of the test capacitor C while the other plate 154 and the underlying tank bottom area serve as the plates of the reference capacitor C The shape of the tank bottom 112 at the location being scanned may be determined by repeatedly operating the electric system, the casing member 152 be ing in a predetermined different position for each operation. Further details of the construction and operation of this modified form of the invention are omitted as being unnecessary for a full understanding of the present spirit of the invention. For example, while, in the form of the invention illustrated in Figure 1, three casing members 152 are shown more or fewer than three could be utilized. In addition, while the reference condensers are shown mounted on the outer end of the frame structure, they could be mounted proximate the center of the tank, over the foundation 116. Furthermore, it may be impossible because of temperature or other reasons to have that part of the electric system shown and described as being housed in the casing 152 in the tank. In this event, the part of the electric system aforesaid may be housed outside of the tank, for example, on the top 114. Still further, while in the exemplary embodiments of the apparatus shown and described scanning is effected through the medium of electrical capacity, scanning may be effected through the medium of other means. For example, sound waves, mechanical or electrical contact feelers or inductance could be utilized.

What is claimed is:

1. In combination, a tank having a horizontally extending bottom rigidly supported in only a portion of its total area and subject to sagging in the unsupported portion of its area; at least one electrode disposed in superposed spaced relation to the tank bottom in the unsupported portion of its area, means connecting said tank bottom and said electrode in electrical circuit thereby to make said electrode one plate of a test condenser and said tank bottom the other plate of said test condenser, another electrode disposed in superposed spaced relation to the tank bottom in the supported portion of its area, means connecting said tank bottom and said other electrode in electrical circuit thereby to make said other electrode one plate of a reference condenser and said tank bottom the other plate of said reference condenser, means connected in circuit with said test and reference condensers for indicating the difference between the capacitance of said test condenser and the capacitance of said reference condenser, and means for moving said one electrode over the unsupported portion of said tank bottom successively to predetermined different positions for scanning the same.

2. The combination defined in claim 1, including also a plurality of electrodes similar to said one electrode and each forming with said tank bottom a respective test condenser; the moving means including a horizontally ex tending elongated carriage member upon which the plurality of electrodes are fixedly mounted, in longitudinally spaced relation to one another.

3. The combination defined in claim 1, wherein the moving means includes a horizontally extending elongated carriage member upon which said one electrode is mounted so as to be selectively positionable along the length of said carriage member.

References Cited in the file of this patent UNITED STATES PATENTS 2,132,407 Fowler Oct. 11, 1938 2,172,368 Eby Sept. 12, 1939 2,574,261 Hagan Nov. 6, 1951 2,829,340 Lippke Apr. 1, 1958 FOREIGN PATENTS 654,908 Germany Dec. 16, 1937 769,806 Great Britain Mar. 13, 1957 

